High temperature lubricant



United States Patent 3,213,024 HIGH TEMPERATURE LUBRICANT Gilbert DuaneBlake, Overland Park, Kans., Rudolph J.

Holzinger, Haddonfield, N.J., and Lawton Eugene Reid,

Kansas City, Mo., assignors to Socony Mobil Oil Company, Inc., acorporation of New York No Drawing. Filed July 17, 1962, Ser. No.210,541

10 Claims. (Cl. 25233.3)

This invention is directed to an improved lubricant composition for usein lubricating materials which must operate at high temperature forextended periods of time and is particularly directed to an improvedlubricant for use on kiln chains.

In the manufacture of many products a final heating or drying step isinvolved. Giant ovens have been developed for continuously conveyingmaterials therethrough which are generally about 300-1000 ft. in lengthand which utilize continuous chains travelling over sprocket wheels toconvey the articles through the heating zone. These kilns operate atapproximately 400- 800 F., depending upon the heat treating conditionsrequired. The heat is supplied by heated air or gas which is circulatedthrough the ovens by fans or blowers suitably located to maintainuniform temperature throughout the oven. These ovens are obviouslyexpensive and their continuous operation is essential or extremelydesirable to the manufacturing operations.

As a specific example of the problems involved, gypsum wall boardcontains a substantial amount of moisture which is put into the stuccoduring the manufacturing operation. These boards must be dried in orderto harden the board prior to stacking and shipping. This dryingoperation is accomplished in an oven or kiln 500 to 700 ft. long. Theboards are carried through the kiln on roll conveyors at approximatelyseven feet per minute. There are six to fourteen conveyors in each kilnstacked one above the other. Each individual roll of the conveyor is ofthe order of 4 or 5 feet long. The many rolls of the conveyor aremounted in bearings and a sprocket is fixed to one end. A chain engagesand moves over the sprocket, rotating the rollers, which in turn slowlypropel the wall board through the kiln. Of course, other designs areused, but they have in common operation of moving parts, generally witha drive chain, at the elevated oven temperature, providing anexceedingly difficult lubrication problem.

The chains are continuous and may extend outside the kiln or in someinstances be contained completely within the kiln. If they extendoutside the kiln, the extension is generally just sufficient to pass thekiln jack at the pull end and far enough on the back end to run over thereturn adjustment idlers. They are, therefore, about twice the length ofthe kiln in which they travel and nine-tenths to all of their 600-2000ft. length is constantly within the kiln and exposed to the high kilntemperatures.

The turbulence created by the circulating hot air in the oven tends tocarry in suspension fine particles of dust, dirt, dried stucco, boardchips, fibers, and other particles from the product undergoing treatmentwhich tend to deposit on the oil wet chain links, and rollers. The oilused to lubricate the mechanism, which previously has been a hydrocarbonoil containing a small amount of graphite, cracks at the hightemperature of the oven producing carbonaceous deposits on the chains.The particles become embedded in the carbonaceous material which acts asa binder and these deposits seriously increase the chain load requiringadditional power to move the chain. These deposits can become so seriousthat they cause the chain to get noisy and may even cause the chain tobuckle and break.

3,213,024 Patented Oct. 19, 1965 ice Chain breakage and damage has beena serious problem in the gypsum wall board industry, the fiber glassindustry and many other industries using these high temperature ovens orkilns. A variety of lubricants has been tested but none has been foundcompletely satisfactory. It is customary, therefore, to permit the chainpower requirement to rise to a critical level and then remove the chainfor cleaning and scraping. This increased power requirement is, ofcourse, expensive. The down time of the oven is expensive andinconvenient since it interrupts the normal flow of the product.

It is an object of this invention to provide a lubricant suitable foruse on equipment operating at elevated temperatures.

It is a further object of this invention to provide a lubricant suitablefor use on equipment operating for sustained periods of time attemperatures of 400800 F.

It is a further object of this invention to provide a lubricant suitablefor use on chains and other members in dusty ovens operating forsustained periods of time at temperatures of 400-800 F.

It is a further object of this invention to provide an improved chainconveyor oven lubricant.

These and further objects of the invention will be more fully disclosedin the following detailed description of the invention.

In accordance with one aspect of this invention a water-in-oil emulsionis formed using an emulsifier suitable for forming such emulsion andusing a high-temperature stabilizer to insure stability of the emulsionat high temperatures of the order of 170200 F. Dispersed in thewater-in-oil emulsion is a finely divided solid lubricant, such asgraphite, molybdenum disulfide, boron nitride, mica, vermiculite, talcumor tungsten disulfite. The emulsion formed by the emulsifier andstabilizer should have an HLB number of broadly about 2-8 and preferablyabout 3-7. The emulsifier and stabilizer can be selected from nonionic,anionic or cationic surfacants.

The oil used is a hydrocarbon oil having a viscosity range of broadly50-1000 SUS at 100 F. The preferred viscosity range, however, is -150SUS at 100 F. The oil generally vaporizes and cracks during thelubrication of the oven conveyor chains and, hence, the Conradson carbonresidue should be broadly less than about 0.25% and preferably less than0.05%. The oil phase of the emulsion, including the emulsifiers may bebroadly about -30% by weight but is preferably about 70-50% by weight. Aparticularly good lubricant formulation is obtained when using a whiteoil with the characteristics given hereinabove.

The emulsifier may be any one of a number of oilsoluble compoundsbroadly classified as anionic, nonionic or cationic. In order to beeffective emulsifying agents, they should be strongly oleophilic, i.e.having an HLB of broadly about 2-6 and preferably 3-5. Surfactantshaving an HLB below about 2 while very strongly oleophilic tend to bepoorer emulsifying agents while those above about 6 tend to form O/Wemulsions or so-called mixed emulsions being partly O/W and partly W/Oand, therefore, unstable. Compounds of the anionic type having beenfound particularly useful are oleophilic alkaline earth petroleumsulfonates, oleophilic alkaline earth naphthalene sulfonates, oleophilicalkaline earth C -C alkyl phenates'and potassium, sodium, ammonium,calcium, barium, strontium, lithium salts of acid phosphates, saidphosphates having been partially neutralized by esterification withabout C C alkyl phenols and ethylene oxide derivatives (2-12 molsethylene oxide) of said phenols. Compounds of the nonionic type havingshown utility are partial esters of polyols and C -C fatty acids, orpartial esters of polyols and so-called wax acids, the latter producedby the oxidation of a mixture of petroleum hydrocarbons having a meancarbon chain length in the range of C C such mixtures commonly beingknown as petrolatum or microcrystalline wax. Particularly good resultshave been obtained with partial esters of sorbitol and its dehydrationproduct such as sorbitan monooleate. These emulsifiers are used at atotal concentration of broadly 0.1-5.0 percent by weight and preferably0.3-3.0 percent by weight.

This lubricant is designed for use on oven conveyor chains and the likeoperating at very high temperatures, such as 400-800 F. It has beenfound that a waterin-oil emulsion provides the best lubrication for thispurpose in that the water droplets are enclosed in oil and hence areable to remain in liquid form for some time period because of theprotective oil cover. Furthermore, oil being the outer phase contactsthe hot metal to provide lubrication to the metal. The metal chain is sohot that the water flashes off as steam on contact thereby providing asubstantial cooling effect and also a blasting effect which effectivelyremoves the hard layer of carbon on the chain. This carbon layer, unlessremoved, builds up to form a tight layer preventing the chain frombending easily and increasing the chain load substantially. However, tobe effective, the emulsion must be delivered to the hot chain in stableform, with the water particles substantially uniformly dispersed in theoil. In order to produce this result in this very hot environment, anemulsion which is exceedingly stable at elevated temperatures must beprovided. The emulsion must remain stable at temperatures as high as170-200 F. to be at all effective. High-temperature stabilizers must,therefore, be used in the lubricant formulation. Suitablehigh-temperature stabilizers are surfactants having an HLB of broadlyabout 8-16 and preferably about 10-15. Among suitable agents of theanionic class, metal soaps of naphthenic acids having molecular weightsof about 315-500 formed from the metals sodium, potassium, ammonium,lithium, calcium, strontium and barium have been found especiallyeflicacious. Also useful are calcium C C alkyl salicylate and C -C alkylphenols. Likewise useful are soaps of G -C and preferably C -C fattyacids from the metals calcium, barium, lithium, strontium, sodium,potassium and ammonium. Also useful are salts of so-called Wax acids orpartial esters of Wax acids and polyols, e.g. the ethanolamine salts orsoaps of these acids or their partial esters. Useful stabilizers of thenonionic type are ethylene oxide derivatives (3-12 mols ethylene oxide)of C -C alkyl phenols, ethylene oxide condensates (1-5 mols ethyleneoxide) of C -C fatty or rosin alcohols and ethylene oxide condensates(4-20 mols ethylene oxide) of partial esters of fatty acids and polyols.Likewise useful are ethoxylated fatty acids and amides, such as oleyl orstearyl amides condensed with about 3-8 mols of ethylene oxide, thelatter being mildly cationic in character. Cationic stabilizers of meritare fatty amines (C -C derived from oleic, palmitic and stearic acidsand modified by condensation with about 2-12 mols of ethylene oxide.Other suitable agents are copolymers of C -C or olefines and vinylalcohol having a molecular weight of 4000-50,000 water solublepolyacrylamide having a molecular weight of 35,000-50,000 and watersoluble polyvinyl pyrollidone having a molecular weight of35,000-50,000. The stabilizers are used at a total concentration 0.1- .0percent by weight and preferably 0.3-3.0 percent by weight.

The amount of high temperature stabilizer needed is based in part uponthe operating condition. For chains operating at the lower end of thetemperature range and where the length of time in the oven is minimum,less stabilizer need be used. This is also influenced in part by themethod of application of the lubricant to the chain. It is essentialthat the lubricant reach the chain in the form of a uniform emulsion sothat the oil phase will provide lubrication and the water droplets willprovide the blasting effect desired. Some of the emulsifiers listedabove show some mild stabilizing effect. Under the milder operatingconditions these emulsifiers may also be used as the stabilizer. Undersevere operating conditions, of course, this is impossible. In anyevent, even under mild conditions, when using the one material as bothemulsifier and stabilizer, the material must be used in substantialamount. The maximum amount is suggested, such as 6-10 percent by weight.

The preferred emulsifiers are the oil-soluble sulfonates. The preferredmaterials for making oil-soluble sulfonates are those obtained bysulfonation of mineral lubricating oil fractions which may be preparedby any of the well known and accepted methods in this art. Calciumpetroleum sulfonate may be used as the emulsifier and may be present inthe blend in the amount of 0.1-5.0 percent by weight of the total blendbut preferably about 0.3-3.0 percent by weight can be used to provideentirely satisfactory results. The calcium petroleum sulfonate, whileprimarily an emulsifying agent, supplies a certain amount ofanti-corrosive action and anti-wear protection. It is preferable thatthe calcium petroleum sulfonate have a molecular weight of at leastabout 900. When the calcium petroleum sulfonate has a molecular weightof about 1000 the emulsification is excellent. Particularly usefulcalcium sulfonates are Calcium Petronate HMW or Basic Calcium PetronateHMW supplied by Sonneborn and Sons, Inc.

It is found that the emulsion will rapidly deteriorate, especially underthe influence of heat, when the calcium petroleum sulfonate is usedalone and hence the mixture of calcium petroleum sulfonate and oil aloneas the oil phase of the lubricant for high temperature use is generallynot satisfactory. As previously indicated, it is found necessary to adda stabilizer to the emulsion which will act to hold the emulsiontogether at elevated temperatures. Unusually stable emulsions are foundto occur when naphthenic acid soaps of sodium, potassium, ammonium,lithium, calcium, barium or strontium are used as the stabilizingmedium. The molecular weight of the naphthenic acid is found to becritical, naphthenic acids of molecular weightless than 275 being foundto possess little or no stabilizing action. Particularly useful arenaphthenic acids of about 275-1000 molecular weight. Outstandinglystable emulsions are obtained when using naphthenic acids identified asSunaptic Acid B and Sunaptic Acid C, using sodium, potassium or lithiumas the soap forming ingredient. The B acid has a molecular weight of325, whereas the C acid has a molecular weight of 415. The C acid issomewhat better than the B acid, although both provide excellentresults. Naphthenic acid identified as Sunaptic Acid A having amolecular weight of 295, on the other hand, was found to provide fairbut still usable stabilization of the emulsion. This lighter acid saltreached optimum stability at a lower concentration but this stabilitywas inferior to the stability obtained with the heavier acid salt andwas more critical than that obtained with the heavier acid salt. Saltsof a naphthenic acid of molecular weight about 250, designated Dhowever, were found to provide little or no benefit regardless ofconcentration, and regardless of whether the sodium, potassium,ammonium, lithium, calcium, strontium or barium salts were used. Thepreferred naphthenic acids are those having molecular weights of about315-500. The concentration of the stabilizing agent in the finishedblend may vary from about 0.1-5 .0 percent by weight but preferablyshould be from about 0.3-3.0 percent by weight.

In order to insure adequate lubrication of the chain and related partsin the hot oven and yet obtain the full cleaning effect of thegasification of the water, the water content in the emulsion must bebetween about 15-70 percent of the water-in-oil emulsion. A preferredwater content is about 30-50 percent by weight of the water-inoilemulsion. The water content in the emulsion has a blasting elfect uponchain deposits, particularly when the chain is operated at the highertemperatures. As the emulsion hits the hot chain the water flashes to agas, causing a rupture and flaking away of the carbonaceous deposits onthe chain. This keeps the chain free and able to flex without strain.Since the water particles are surrounded by oil, however, the oilprovides lubrication to the chain and its moving parts and protects thechain from detrimental contact with water at elevated temperature.

It is essential for proper lubrication of these hot oven chains to havedispersed in the emulsion lubricant a solid lubricant such as graphiteor molybdenum disulfide or tungsten disulfide or boron nitride or micaor vermiculite or talcum which is dispersed in the oil phase and remainson the chain after the intense heat has altered or driven otf theremainder of the lubricant. Of the solid lubricants mentioned, thepreferred solid lubricants are graphite, molybdenum disulfide andtungsten disulfide, with the most preferred solid lubricant beinggraphite. The solid lubricant can be dispersed in an oil or distillatehydrocarbon in concentrated form for admixture with the emulsion or itcan be distributed directly with the oil by well known procedures. Thegraphite or other solid lubricant may or may not be mixed with asatisfactory graphite dispersant, depending upon mixing procedure, typeof emulsion selected viz concentrated or dilute, and the decision to usea graphite dispersant may also depend in part upon the conditions underwhich the water-in-oil emulsion will be used and the oven operatingconditions. Skill in blending and using graphite containing water-in-oilemulsions can be rapidly acquired, bearing in mind that a deposit of thegraphite must be laid down on the hot chain to insure adequatelubrication and the graphite dispersant must be compatible with theemulsifier system. The dispersed solid lubricant, such as graphite,should be added in the amount of broadly 0.055% and preferably 0.1- 2%by Weight of the final composition. The graphite may be supplied firstas a 1 part in ten dispersion in light oil or naphtha. This dispersioncan. then be readily mixed with the remainder of the emulsion lubricantto provide the finished blend. The particle size of the solid lubricantshould be broadly 0.25 to 50 microns but preferably 0.5 to 5 microns.

. Example 1 A conventional prior art oven conveyor lubricant was usedconsisting of 37.9% by volume of a paraffin oil having a viscosity of 60SUS at 100 F., 56.7% by volume of a naphthenic oil having a viscosity of100-110 SUS at 100 F. and 5.2% by volume of a colloidal graphite dispersion containing 1 part of graphite in 9 parts of mineral spirits(particle size about 2 microns). This lubricant, when used on ovenconveyorchains operating at tem peratures over about 400 F., used in themanufacture of fiber glass, produced a very hard carbon formation on thechain which ultimately caused the links of the chain to freeze. Some ofthe links would then wear excessively so that flat spots occurred in thechain. Furthermore power consumption greatly increased after the hardcarbon formation occurred making it necessary to remove the chains forcleaning and replacement of worn links. This is an extremely expensiveproposition amounting to as much as $10,000 per year per chain.

Example 2 A fine stable water-in-oil emulsion lubricant for ovenconveyor chains can be formed by mixing 1 percent by weight ofoil-soluble calcium petroleum sulfonate as the basic emulsifier, 41.5percent by weight of water, 0.8 percent by weight potassium naphthenate(using naphthenic acid of 325 M.W.) as the stabilizer, 0.5 percent byweight colloidal graphite and the balance paratfin oil having aviscosity of about 100 SUS at 100 F. The mixture is emulsified by a wellknown method and is then ready for use. As a test of stability, a sampleof this emulsion was placed in a tall 4 oz. oil sample bottle up to alevel of mm. and subjected to a seven day storage test at 170 F. Thewater separated was nil and the oil separated was about 7 mm. Thislubricant, when applied to high temperature oven conveyor chains, does asuperior lubricating job when compared to the prior art lubricant ofExample 1.

Example 3 Another fine stable water-in-oil emulsion lubricant for ovenconveyor chains was formed in the following manner:

Two-thirds of the total amount of oil to be used, i.e. 52.05% by weight,was charged to a steam heated kettle equipped with mechanical agitation.The oil used was a medicinal white oil having a viscosity of about 1 ,10SUS at 100 F. To this oil were added 0.19% by weight of naphthenic acid(M.W. 295), 0.19% by weight of naphthenic acid (M.W. 415), and 0.10% byweight of hydrogenated marine oil fatty acids. The mixture was heated toF. to F. and 0.10% by weight of glacial acetic acid was added, followedby 0.39% by weight of caustic potash solution (45% by weight activematerial), the blend was stirred for an additional 15 minutes whereuponthe temperature was raised to 190 F. At this point 2.37% by weight ofbasic calcium petroleum sulfonate (9701000 M.W.; 40-45% active) wasadded and the temperature raised to 260 F. This temperature wasmaintained for 510 minutes and the batch quenched with the remainingone-third of the mineral oil. While adjusting the batch temperature to175-185 F., 0.48% by weight of a mixture of octylated diphenyl amineswas added. 39.83% by weight of water was heated in a separate kettle andadded to the oil phase over a period of 15-30 minutes and vigorousagitation. After homogenizing to insure small particle size of the waterdroplets, the emulsion was cooled and 4.30% by weight of colloidalgraphite dispersion (1 part graphite in 9 parts of mineral spirits) wasadded. The resultant preparation had excellent stability at temperaturesof about 200 F.

Example 4 A portion of the lubricant of Example 3 was supplied to acommercial oven chain used in the curing of fiber glass. This ovenmeasured approximately 85 feet in length, 10 feet in width, and 10 feetin height. The oven contained two conveyor flightsupper andlowerextending almost the full length of the oven. The lower flight wasfixed but the upper flight was adjustable in height to provide a meansof controlling the thickness of the mat. The sprockets were locatedwithin the oven and at each end of the oven. The sprockets measuredabout 3 ft. in diameter and were about 90 ft. apart, giving a totalchain length of about 200 ft. Since four chains were located in thisoven the total chain length measured about 800 ft. The oven conveyorswere driven by an Oilgear hydraulic unit, the hydraulic pressure varyingfrom 400- 1200 p.s.i. (gauge) according to the load factors. Given a setoperating condition, the only variable was the efiectiveness of thelubrication or the carbon build-up on the chain. The 400 psi. is roughlyequivalent to 60 horsepower whereas the 1200 p.s.i. is roughlyequivalent to 120 horsepower requirement. The oven was maintained atabout 400600 F. during the test operation.

The test lubricant was pumped intermittently and discharged underpressure onto the link of the chain in an amount to supply suflicientlubricant. Before the test lubricant was applied the chains had beenlubricated with the oil of Example 1 and a heavy deposit of carbonaceousmaterial mixed with fiber glass had built up on the chain. When the testlubricant was substituted the deposits on the chain commenced todecrease. The hydraulic pressure of the drive unit gradually reducedfrom over 1000 p.s.i., to about 700-800 p.s.i. at the same generaloperating conditions.

7 Example In two other installations using a convention prior lubricantsimilar to the lubricant of Example 1, hydraulic pressure had built upgradually until it reached relief pressure over about 1100 p.s.i.(gauge), and the unit automatically shut down. Upon changing to thelubricant shown in Example 3, this pressure was reduced to about 500p.s.i. (gauge) over a period of less than two weeks and subsequentlydecreased to 400 psi. (gauge), indicating that horsepower requirementswere reduced by almost fifty percent.

Example 6 A test of the lubricant of Example 1 without the graphite wasmade on the oven chains described in Example 3. The lubrication of thechain was found to be inferior and the chain commenced to squeal frominadequate lubrication. This test had to be discontinued to preventdamage to the equipment from lack of lubrication.

It had been estimated that the use of the water-in-oil lubricant of thisinvention will prolong the active life of these high temperature ovenconveyor chains from about one year to about two years. Since the chainsare expensive and down time is expensive, the economic advantage ofusing this lubricant is measured in many thousands of dollars in savingto the user.

Example 7 A suitable oven conveyor lubricant is obtained by mixing 0.5%by weight basic calcium salicylate, 0.5% by weight basic calciumpetroleum sulfonate, about 35% by weight water, 0.5% by weight dibenzyldisulfide, 0.5% by weight glycerol mono-oleate, 0.5% by weight colloidalgraphite and 62.5% by weight of a naphthenic petroleum oil having aviscosity of about 200 SUS at 100 F. The materials are mixed andemulsified by methods known in the art and a satisfactory stableemulsion is formed which remains stable at elevated temperatures.

Example 8 A suitable oven conveyor lubricant for high temperatureoperation is obtained by mixing 1.5 percent by weight lithiumnaphthenate (using a naphthenic acid having a molecular weight of 415),0.5% by weight of calcium petroleum sulfonate (about 1000 molecularweight), 70% by weight of petroleum White oil, 5% by weight of colloidalgraphite in naphtha or 0.5 percent by weight graphite), and 33 percentby weight of water. The ingredients are emulsified by procedures wellknown in this art to yield a high stable water-in-oil emulsion lubricantsuitable for high temperature duty and oven conveyor chains.

Example 9 An oil-in-water emulsion lubricant containing about 1 part oiland 3 parts water (using a conventional oil-inwater emulsifier system)was combined with about 0.5% by weight of the final formulation ofcolloidal graphite and tested on the commercial oven disclosed inExample 3. It was soon noted that the power requirement increased,indicating inadequate lubrication and the formation of hard carbon onthe chains. The chains began to squeal noticeably. After several daysoperation the power requirement had increased to such an extent that thetest was discontinued to prevent damage to the chains. Reuse of thelubricant of Example 2 stopped the squealing of the chain and broughtthe power requirement back to the level prevailing before this test wascommenced.

Example 10 An oil-in-water emulsion lubricant containing about equalparts of oil and water (using a conventional oil in-water emulsifiersystem) was combined with about 0.5% by weight of the final formulationof colloidal graphite and tested on the commercial oven disclosed inExample 3. The results were very similar to those disclosed in Example9'.

Example 11 A fine stable water-in-oil emulsion lubricant was formed bymixing 2.36% by weight of basic calcium petroleum sulfonate (9701000M.W.; 40-45% active), 0.95% by weight of naphthenic acid (M.W. 415), and0.58% by weight of caustic potash solution (20% active) withapproximately one-third of a total of 51.77% by weight of solventrefined paraffin (about SUS at 100 F.). This mixture was heated to aboutF. and the remaining two thirds of the base oil was added. Subsequently,0.42% by weight of a mixture of octylated diphenyl amines and 4.72% byweight of colloidal graphite dispersion (one part graphite in nine partsmineral spirits) were blended into the mixture. Finally 39.20% by weightof water previously heated to about 150 F. was added with rapidagitation. A sample of the resulting fine particle emulsion was storedat F. Examination after five days showed no water separation and only2.5% of free oil. The same sample after eleven days still showed noseparation of water and only 5.0% of supernatant oil. It will beappreciated that in water-in-oil emulsions separation of oil is a minordeficiency since it can easily be mixed with the remaining emulsion bymild agitation inasmuch as the oil constitutes the continuous or outerphase. Another sample of the above described oven conveyor lubricant wasstored at a temperature close to the boiling point of water, i.e. at 200F. This sample, which was stored under such severe conditions, wasexamined at similar time intervals (5 days; 11 days) and after five daysstill exhibited no free water and only 3% of free oil; after a total ofeleven days of exposure water separation amount to about 1.5% and oilseparation to about 8%. The outstanding heat stability of this materialmakes it of particular utility for use as a high-temperature,ovenconveyor lubricant.

Example 12 A fine stable high-temperature oven-conveyor lubricant isformed by mixing 1.8% by weight of sorbitan monooleate, 1.2% by weightof polyoxyethylene sorbitan trioleate (20 mols of ethylene oxide), 52.0%by weight of solvent refined naphthenic petroleum oil of a viscosity of100 SUS at 100 F., 3-4 ppm. of a defoamant (Dow Corning Fluid 200-12,500centipoises) and 5% by weight of colloidal graphite (one part graphiteto nine parts mineral spirits). This lubricant was stored for 40 hoursat 170 F. and showed no water separation and only 2% oil separation.This lubricant is an excellent lubricant for hot oven conveyor chains(operating at 400800 F.).

Example 13 Another fine stable high-temperature oven-conveyor lubricantwas formed by mixing 2.5 by weight of sorbitan mono-oleate, 0.5% byweight of the condensation product of oleyl amide and 5 mols of ethyleneoxide, 47% by weight of a solvent-refined naphthenic petroleum oilhaving a viscosity of 100 SUS at 100 F., 0.1% by weight of a defoamant(Dow Corning 200 Fluid, 1000 centipoises, 10% solution in kerosine), 49%by weight of water and 1% by weight of molybdenum disulfide (96% oftotal number of particles below 2 microns in size). This lubricant wasstored at 170 F. for 24 hours and showed no water separation and only 3%oil separation. This formulation is an excellent conveyor chainlubricant for chains operating at temperatures in the range of 400-800F.

The test program conducted has demonstrated that oven conveyor chainsoperating at temperatures over 300 F. and more particularly attemperatures of 400-800 F. require for maximum performance awater-in-oil emulsion in which a stabilizer is used with the baseemulsifier to provide a stable emulsion at temperatures as high as 9 170F.-200 F. This program has shown that a solid lubricant, such ascolloidal graphite, molybdenum disulfide, tungsten disulfide, boronnitride, or the like, must be dispersed in the emulsion to provideadequate lubrication of the chains. The lubricant, for most efiicientlubrication, should be provided either intermittently, or continuouslyto the chain without a long dwell period in the oven.

The examples given hereinabove were presented only to illustrate theinvention and are not intended to limit the scope of the invention. Theonly limitations are contained in the following claims.

We claim:

1. A lubricant for use at elevated temperatures on oven conveyor chainsand the like in the form of a water-in-oil emulsion which comprisesabout 0.1- percent by weight, sufficient to emulsify the water and oil,of an oleophilic anionic emulsifier possessing an HLB number of about2-6, about 0.1-5 percent by weight of a high-temperature ionicstabilizer for said emulsion possessing an HLB number of about 8-16, thecombined emulsifier and stabilizer having an HLB number of about 2-8,the oil portion of said emulsion being a hydrocarbon oil possessing aConradson carbon residue less than about 0.25% and of from about 50-1000SUS viscosity at 100 F. in the amount of about 85-30 percent by weight,the water content of said emulsion being about 15-70 percent by weight,and about .05-5 percent by weight of a solid lubricant in finely dividedform having a particle size from about 0.25 to 25 microns said lubricantbeing dispersed in the water-in-oil emulsion and normally adapted tobecome deposited on the said oven conveyor chains at elevatedtemperatures.

2. A lubricant for use at elevated temperatures on oven conveyor chainsand the like in the form of a waterin-oil emulsion which compries about0.3-3 percent by weight, sufficient to emulsify the water and oil, of ananionic emulsifier possessing an HLB number of about 2-6, about 0.3-3percent by weight of a high-temperature anionic stabilizer for saidemulsion possessing an HLB number of about 8-16, the combined emulsifierand stabilizer having an HLB number of about 3-7, the oil portion ofsaid emulsion being a hydrocarbon oil possessing a Conradson carbonresidue less than about 0.25% and of from about 80-150 SUS viscosity at100 F. in the amount of about 70-50 percent by weight, the Water contentof said emulsion being about 30-50 percent by weight, and about 0.1-2percent by weight of a solid lubricant in finely divided form having aparticle size from about 0.25 to 25 microns said lubricant selected fromthe group consisting of graphite, molybdenum disulfide, boron nitride,mica, vermiculite, talcum and tungsten disulfide.

3. A lubricant for use at elevated temperatures on oven conveyor chainsand the like in the form of a water-in-oil emulsion which comprisesabout 01-5 percent by Weight, sufiicient to emulsify the water and oil,of an emulsifier possessing an HLB number of about 2-6 and selected fromthe group consisting of oleophilic alkaline earth petroleum sulfonates,oleophilic alkaline earth naphthalene sulfonates and oleophilic alkalineearth C C alkyl phenates, about 0.1-5 percent by weight of ahigh-temperature stabilizer for said emulsion possessing an HLB numberof about 8-16 and selected from the group consisting of metal soaps ofnaphthenic acids having molecular weights of about 315-500 formed fromthe metals sodium, potassium, ammonium, lithium, calcium, strontium andbarium, calcium C -C alkyl salicylate, C C alkyl phenol, copolymers of C-C a-olefines and vinyl alcohol having a molecular weight of 4000-50,000, water-soluble polyacrylamide having a molecular Weight of35,000-50,000, water-soluble polyvinyl pyrrolidone having a molecularweight of 35,000-50,000, oilsoluble partial esters of polyhydric alcoholand C -C fatty acid, soaps of O -C fatty acids formed from the metalspotassium, sodium, ammonium, lithium, calcium, strontium and barium inthe amount of about -30 percent by weight, the water content of saidemulsion being about 15-70 percent by weight, and about .05-5 percent byWeight of a solid lubricant in finely divided form having a particlesize about from 0.25 to about 25 microns said lubricant being dispersedin the water-in-oil emulsion and normally adapted to become deposited onthe said oven conveyor chains at elevated temperatures.

4. The composition of claim 3 further characterized in that the solidlubricant is selected from the group consisting of graphite, molybdenumdisulfide, boron nitride, mica, vermiculite, talcum and tungstendisulfide.

5. A lubricant for use at elevated temperatures on oven conveyor chainsand the like in the form of a Water-in-oil emulsion which comprisesabout 0.1-5 percent by weight, sufficient to emulsify the water and oil,of an emulsifier possessing an HLB number of about 2-6 and selected fromthe group consisting of potassium, sodium, ammonium, calcium, strontium,barium, lithium salts of acid phosphates, said phosphates having beenpartially neutralized by esterification with C -C alkyl phenols andethylene oxide derivatives containing 2-1@ mols ethylene oxide of saidphenols, about 0.1-5 percent by weight of a stabilizer for said emulsionpossessing an HLB number from about 8-16 and selected from the groupconsisting of ethylene oxide condensates containing 1-5 mols of ethyleneoxide of C -C fatty and rosin alcohols, in the amount of about 85-30percent by weight, the water content of said emulsion being about 15-70percent by weight and about .05-5 percent by weight of a solid lubricantin finely divided form having a particle size from about 0.25 to about25 microns said lubricant being dispersed in the water-in-oil emulsionand normally adapted to become deposited on the said oven conveyorchains at elevated temperatures.

6. The composition of claim 5 further characterized in that the solidlubricant is selected from the group consisting of graphite, molybdenumdisulfide, boron nitride, mica, vermiculite, talcum and tungstendisulfide.

7. A lubricant for use at elevated temperatures on oven conveyor chainsand the like which comprises a water-in-oil emulsion containing about25-45 percent by Weight water, about 0.25-2.00 percent by weight ofoilsoluble calcium petroleum sulfonate as an emulsifying agent, about0.25-3.0 percent by weight of metal soaps of naphthenic acids havingmolecular weights of about 315-500 as a stabilizer, the metal beingselected from the group consisting of sodium, potassium, ammonium,lithium, calcium, strontium, and barium, the oil portion of saidemulsion being a hydrocarbon oil possessing a Conradson carbon residueof less than about 0.25% of from about 50-400 SUS viscosity at 100 F.,the ratio between the oil-soluble calcium petroleum sulfonate and themetal naphthenate being from 5/95 to /5 by weight, and about 0.5 percentby weight of colloidal graphite.

8. The composition of claim 7 further characterized in that the metalsalt is potassium naphthenate.

9. The composition of claim 7 further characterized in that the oil is awhite oil.

10. A lubricant for use at elevated temperatures on oven conveyor chainsand the like which comprises a water-in-oil emulsion containing about25-45 percent by weight water, about 01-50 percent by weight of sorbitanmono-oleate, about 0.1-5 .0 percent by weight of a partial ester of apolyhydric alcohol and a C -C fatty acid, said ester being condensedwith about 4-20 mols of ethylene oxide, 0.5 percent by weight of a solidlubricant selected from the group consisting of graphite, molybdenumdisulfide and tungsten disulfide having a particle size from about 0.25to 50 microns, the balance being a petroleum hydrocarbon oil having aviscosity of about SUS at 100 F. and a Conradson carbon residue lessthan about 0.05 percent.

(References on following page) 1 1 1 2 References Cited by the Examiner2,961,404 11/60 Francis 252-49.5 X UNITED STATES PATENTS 3,019,190 1/ 62Holzinger 252-333 X 1,898,809 2/33 Berg 134*17 X 3,052,629 9/62 MOTfOWet :al. 252--49.5 1,984,771 12/34 speller. 5 FOREIGN PATENTS 2,156,8035/39 COQPCI et a1. 25225 09 725 10 4 Great Britain Whlte et a1 GreatBritain. Nul'ln et a1- Canada 2,744,870 5/56 Stillebroer et a1. 25249.5X 2,842,837 7/58 Huet et X 10 DANIEL E. WYMAN, Primary Examiner.

2,894,910 7/59 Francis et a1 25249.5 X

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,213,024 October 19, 1965 Gilbert Duane Blake et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, line 34, for "disulfite" read a disulfide column 6, line 35,for "and" read with line 45, for "85" read 95 column 7, line 20, for"had" read ha column 8, line 35, for "amount" read amounted .Signed andsealed this 14th day of June 1966,

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER \ttesting Officer Commissioner ofPatents

3. A LUBRICANT FOR USE AT ELEVATED TEMPERATURES ON OVEN CONVEYOR CHAINSAND THE LIKE IN THE FORM OF A WATER-IN-OIL EMULSION WHICH COMPRISESABOUT 0.1-5 PERCENT BY WEIGHT, SUFFICIENT TO EMULSIFY THE WATER AND OIL,OF AN EMULSIFIER POSSESSING AN HLB NUMBER OF ABOUT 2-6 AND SELECTED FROMTHE GROUP CONSISTING OF OLEOPHILIC ALKALINE EARTH PETROLEUM SULFONATES,OLEOPHILIC ALKALINE EARTH NAPHTHALENE SULFONATES AND OLEOPHILIC ALKALINEEARTH C3C18 ALKYL PHENATES, ABOUT 0.1-5 PERCENT BY WEIGHT OF AHIGH-TEMPERATURE STABILIZER FOR SAID EMULSION POSSESSING AN HLB NUMBEROF ABOUT 8-16 AND SELECTED FROM THE GROUP CONSISTING OF METAL SOAPS OFNAPHTHENIC ACIDS HAVING MOLECULAR WEIGHTS OF ABOUT 315-500 FORMED FROMTHE METALS SODIUM, POTASSIUM, ANMMONIUM, LITHIUM, CALCIUM, STRONTIUM ANDBARIUM, CALCIUM C8-C30 ALKYL SALICYLATE, C4-C18 ALKYL PHENOL, COPOLYMERSOF C10-C40 A-OLEFINES AND VINYL ALCOHOL HAVING A MOLECULAR WEIGHT OF400050,000, WATER-SOLUBLE POLYACRYLAMIDE HAVING A MOLECULAR WEIGHT OF35,000-50,000, WATER-SOLUBLE POLYVINYL PYRROLIDONE HAVING A MOLECULARWEIGHT OF 35,000-50,000, OILSOLUBLE PARTIAL ESTERS OF POLYHYDRIC ALCOHOLAND C8-C32 FATTY ACID, SOAPS OF C16-C30 FATTY ACIDS FORMED FROM THEMETALS POTASSIUM, SODIUM, AMMONIUM, LITHIUM, CLACIUM, STRONTIUMM ANDBARIUM IN THE AMOUNT OF ABOUT 85-30 PERCENT BY WEIGHT, THE WATER CONTENTOF SAID EMULSION BEING ABOUT 15-70 PERCENT BY WEIGHT, AND ABOUT .05-5PERCENT BY WEIGHT OF A SOLID LUBRICANT IN FINELY DIVIDED FORM HAVING APARTICLE SIZE ABOUT FROM 0.25 TO ABOUT 25 MICRONS SAID LUBRICANT BEINGDISPERSED IN THE WATER-IN-OIL EMULSION AND NORMALLY ADAPTED TO BECOMEDEPOSITED ON THE SAID OVEN CONVEYOR CHAINS AT ELEVATED TEMPERATURES.